Ok, Now That I've Thought About It, The 2019 Ranked System is Genius.
tldr at bottom
Ok, so this new ranked system sounds pretty good to me because it would accurately reflect people's skill but there is something that people are thinking is an exploit but it's not. Here's why.
What people are thinking of as an exploit is the so called ROLE SWAP EXPLOIT.
It goes like this. One person that is at a high ELO for their main role queues up for a role that isn't their main and gets into a lobby. They tell the person that is supposed play their role that they are at a significantly higher rank in that position and it would be any easy game if they were to trade with them.
The person that is supposed to play the role thinks to themselves that it would be great if they could get some free LP so they think about it.
After thinking, they realize that if they swapped, they wouldn't get LP on their main role if they swapped with this highly ranked player, so they don't swap because they want to rank up their main role.
See, there are no exploits to worry about that I can see with the positional ranking. Riot just used some simple logic applied to basic human psychology to think of a system that would work. Geniuses (opinion)!
Also, Riot could make it so that role swapping isn't possible, only champion swapping is so people can pick champions for you.
Well, that's all I got and have a GREAT DAY! :)))))))))))))))))))))))))))))))))))))))))))
tldr: People will not swap because they want to rank up their main role.